Yeah I've had the opportunity to hear a Raptor when it visited MacArthur Airport on Long Island. You KNOW when a F-22 is in the air! Great shots for an "entry level" lens. Especially 155 thru 177. Need to get a bigger zoom len's on my digital camera myself.

Lightndattic wrote:It's not normal for the APU to be running while taxi-ing, is it?

According to a previous mishap report, no it isn't. The main reason why he'd do that, is in order to temporarily shut down one or both engines. I'm 90% sure that the F-22 will experience "degraded" electrical supply with one generator(engine) running, unless the electric bus is "tied". Running the APU is insurance against certain problems on one generator.

The F/A-18F NATOPS (Anyone have a F-22 Flight Manual?) has procedural restrictions on APU use in flight (and on the ground) due to overheat risk, but when you're down to one engine (generator) running the APU makes sense. If the pilot of the Miramar F/A-18D mishap pilot had started his APU, the fatal outcome might have been different, even if the jet was still lost. In that case, the pilot was completely unable to control the jet, and dropped like a brick. I'm not second-guessing the pilot, as the NATOPS did not expressly require the APU start, for single-engine ops. From what I recall, airborne APU start is only recommended in single-engine ops where loosing the second engine is likely for the conditions. Dual flame-out NATOPS procedures requires APU start, unless windmill start is advised, for restart, otherwise the pilot will have to eject.

I don't have exact procedures for the F-22, but one possibility is that the pilot wanted to keep certain electronics fully powered for full maintenance investigation, and/or a dual generator failure was the cause of the incident.

Edit: I do not have direct information with regards to this F-22 incident other than what is published. I'm only stating my interpretation/opinion.